Carburetor fuel transfer discharge port

ABSTRACT

A carburetor having an induction passage with a variably positionable throttle valve situated therein has an idle fuel discharge port situated downstream of the throttle valve, when the throttle valve is in its curb idle position, and a transfer port or slot for discharging fuel into the induction passage as the throttle valve is moved from its curb idle position toward a more fully opened position; the transfer port or slot is formed of a generally hollow body-like member inserted in the structure defining the carburetor so as to have a slot which is formed in the body-like member in communication with the induction passage and the interior space of the hollow body-like member; a plug is inserted within the interior space of the body-like member and the slot and located as to thereby define a terminal portion of the slot in a location precisely as required with respect to the throttle valve when the throttle valve is in its curb idle position.

United States Patent [191 Dreher Mar. 12, 1974 CARBURETOR FUEL TRANSFERDISCHARGE PORT James H. Dreher, Durham, NH.

[73] Assignee: Colt Industries Operating Corp.,

- New York, NY.

[22] Filed: Aug. 17, 1972 [21] Appl. No.: 281,444

[75] Inventor:

Primary Examiner-Tim R. Miles [57] ABSTRACT A carburetor having aninduction passage with a variably positionable throttle valve situatedtherein has an idle fuel discharge port situated downstream of thethrottle valve, when the throttle valve is in its curb idle position,and a transfer port or slot for discharging fuel into the inductionpassage as the throttle valve is moved from its curb idle positiontoward a more fully opened position; the transfer port: or slot isformed of a generally hollow body-like member inserted in the structuredefining the carburetor so as to have a slot which is formed in thebody-like member in communication with the induction passage and theinterior space of the hollow body-like member; a plug is inserted withinthe interior space of the body-like member and the slot and located asto thereby define a terminal portion of the slot in a location preciselyas required with respect to the throttle valve when the throttle valveis in its curb idle position.

9 Claims, 8 Drawing Figures CARBURETOR FUEL TRANSFER DISCHARGE PORTBACKGROUND OF THE INVENTION As is well known in the art, carburetorsemploy, among other systems, an idle fuel system and a main fuel system.The main fuel system usually comprises a main fuel discharge nozzle(cooperating with related metering restriction means) situated generallywithin the throat of a venturi section of the induction passage and istherefore responsive to and effective for discharging fuel in accordancewith the ventrui vacuum generated by the flow of air therethrough.However, generally, at low engine speeds, including idle engineoperation, the velocity of air flow through the venturi is insufficientto create a suitable metering vacuum.

Therefore, the idle fuel delivery system, which comprises an idle fueldischarge port'communicating with the induction passage downstream ofthe throttle valve when in its idle position, in employed to provide therequired fuel during the lower range of engine operation. The idle fuelsystem, by virtue of the location of the idle fuel discharge port, isexposed and responsive to the value of the engine intake manifold vacuumgenerated downstream of the throttle. It should also be remembered that,with certain possible exceptions, the value of the vanifold vacuum willbe the greatest at idle and will diminish as the throttleisprogressively moved in an opening direction. Therefore, with merely afixed idle fuel discharge port, the fuel-air mixture would become leanerin-fuel as the throttle were moved in the opening direction because ofthe fixed discharge area of the idle fuel discharge port and thereduction in the value of manifold vacuum.

Consequently, in order to provide a smooth transistion from the idlefuel system (responsiveto engine vacuum) to the main fuel system(responsive to venturi vacuum created after air flow has attained apredetermined velocity) the prior art has provided a fuel transfer portor slot communicating with the induction passage and supplied with fuelgenerally from the idle fuel system. Although the exact position of thelower or terminal end of the transfer slot orport is often dependent onthe particular characteristics of the engine which is to employ thecarburetor, generally, the transfer slot is so located within theinduction passage as to be traversed by an edge of the throttle valve asthe throttle valve is being moved toward a more fully opened position.In so traversing the transfer port, the manifold vacuum existingimmediately below the throttle valve is permitted to act on theprogressively increasing exposed area of the transfer slot therebyincreasing fuel flow therethrough and into the induction passage.

Although in years past the transfer slots or ports of the prior art haveproven to be generally satisfactory, they are now found to beunsatisfactory especially in view of the automotive industrys concernwith reducing the level of engine exhaust emissions.

That is, in accordance with the accepted practice, such transfer slotsor ports were cut into the body forming the carburetor by a machiningprocess which, as is of course obvious, requires certain dimensionaltolerances. Other manufacturing tolerances are, of course, required asfor example with respect to the location of .the throttle shaft, thesize of the throttle shaft at the point where it supports the throttlevalve, the size and configuration of the throttle valve, and the size ofthe induction passage itself. All of such tolerances often result inhaving the terminal end of the transfer slot located not exactly whereit should be with respect to the edge of the throttle valve when thethrottle valve is in its idle position. Depending on where such terminalend actually occurs will also often determine whether the carburetorwill have an overly rich fuel-air mixture or even dead-spots during thetime that the throttle valve starts traversing the transfer port.

Accordingly, the invention as herein disclosed is primarily concernedwith the solution of the above as well as other related problems.

SUMMARY OF THE INVENTION According to the invention, apparatus fordefining a fuel discharge port in a fuel supply device having a housingwith an induction passage formed therethrough and a variablypositionable throttle valve situated within said induction passage,comprises a body adapted to be inserted into a receiving opening formedin said housing, a first passage formed in said body for communicationwith a source of fuel, a slot-like open- DESCRIPTION OF THE DRAWINGS Inthe drawings, wherein for purposes of clarity certain details andelements may be omitted from one or more views:

FIG. 1 is a top plan vies of a throttle body portion of a multiinductionpassage carburetor employing the invention; Y

FIG. 2 is an enlarged fragmentary cross-sectional view taken generallyon the plane of line 2 -2 of FIG. 1 and looking in the direction of thearrows;

FIG. 3 is an enlarged fragmentary cross-sectional view taken generallyon the plane of line 33 of FIG. 1 and looking in the direction of thearrows;

FIG. 4 is an enlarged fragmentary cross-sectional view taken generallyon the plane of line 4-4 of FIG. 1 and looking in the direction of thearrows;

FIG. 5 is a somewhat enlarged exploded perspective view of certain ofthe elements shown in FIG. 3;

FIGS. 6 and 7 are views somewhat similar to that of FIG. 5 butillustrating other embodiments; and

FIG. 8 is a fragmentary perspective view of a modified form of one oftheelements comprising the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in greater detailto the drawings, FIG. 1, by way of example, illustrates a throttle body10 having primary bores or induction passage portions 12 and 14 andsecondary bores or induction passage portions 16 and 18. A primarythrottle shaft 19 journaled within the throttle body 10, and extendingtransversely through the induction passages 12 and 14, has securedthereto primary throttle valves and 22 respectively located within bores12 and 14. Similarly, 'a secondary throttle shaft 24 journaled withinthe throttle body 10, and extending transversely through the inductionpassages 16 and 18, has secured thereto secondary throttle valves 26 and28 respectively located within bores 16 and 18. Throttle shafts l9 and24 may be provided with suitable control linkage means respectivelyfragmentarily illustrated at 30 and 32.

Groove-like channels 34 and .36 may be formed in the upper surface ofthrottle body 10 so as to receive therein fuel from the related idlefuel system and, in turn, distribute such fuel to conduit portionsleading to idle fuel discharge ports. For example, channel 34communicates at its opposite ends with downwardly extending conduitportions 38 and 40 respectively communicating and feeding idle fueldischarge ports 42 and 44 while channel 36 communicates at its oppositeends with similar downwardly extending conduit portions 46 and 48communicating and feeding similarly situated idle fuel discharge ports50 and 52.

As generally typically illustrated in FIG. 2, a main carburetor body 54(fragmentarily illustrated) may be carried atop the throttle body 10 ina manner containing a suitable seal or gasket-56 therebetween with thegasket, among other things, serving to close off the upper portion ofthe channels 34 and 36 except, of course, at the point where they arefed by the idle fuel system. Similarly,,a gasket or sea] 58 may beprovided and contained between the lower surface of throttle body 10 andthe upper surface of the engine intake manifold 60 to which the throttlebody 10 is secured.

Considering FIGS. 1, 3 and 5, it can be seen that the transfer portmeans 62 is comprised of a hollow-like insert body 64 and a cooperatingplug 66 which are received within a slot or recess 68 formed in thethrottle body 10. As best seen in FIG. 5, insert body 64 may becomprised as to have parallel external side walls 70, 72, end wallportions 74, 76 parallel to end wall and top and bottom walls 78 and80through which a-passageway 82 extends.

Body 64 is also provided with a rib-like extension 84 which has anoutwardly directed surface 86 preferably of an arcuate configureationconforming to the radius of the induction bore 12. A slot 88 is formedthrough the rib 84 so as to communicate with the main internal passage82. i

As generally illustrated in FIGS. 1 and 3, recess or receiving groove 68may be formed through throttle body 10 and have a cross-sectionalconfiguration closely approximating the cross-sectional configuration ofthe insert body 64.

The plug 66, shown in each of FIGS. 1, 3 and 5, may be comprised of amain body portion having an outer contoured surface 90 closelyconforming to'the crosssectional configuration of passage 82 of insertbody 64. A rib-like protrusion or extension 92, carried by the body ofplug 66, has an outer surface 94 which is preferably contoured to form acontinuation of the contour of surfaces 86. The ends of plug 66 aredetermined by end surfaces 96 and 98. As generally illustrated by FIGS.1 and 3, plug 66 is received within passageway 82 of insert body 64 in amanner causing the rib portion 92 to be closely received within slot 88of body 64.

As best shown in FIG. 3, insert body 64, which may be formed of asuitable plastic, is preferably positioned so as to have its upper mostsurface 78 abutting against the lower surface of gasket 56 and tothereby have the upper portion of its inner passage 82 in communicationwith suitable conduit means 100 leading to a source of fuel (not shownbut well known in the art). The body 64 may be suitably fixed in placewithin the groove or recess 68, in the position shown, as by employing,for example, a suitable adhesive for cementing body 64 to receivingrecess 68.

The plug 66 is generally slideably received within passageway 82, andslot 88, and moved axially therewithin until the top surface 96 thereofis positioned in a desired relationship with respect to the edge of thethrottle valve 20 when the throttle valve is in its idle position. Forpurposes of illustration, and not by way of limitation, this has beenshown as having top surface 96 of plug 66 at a level half way betweenthe upper and lower surfaces of the edge of the throttle valve 20.

Plug 66 may also be made of plastic and, after adjustment, fixed inplace within body 64 by, for example, employing a suitable adhesive forsementing the plug 66 to the insert body 64.

As a consequence, fuel passage means are defined by conduit means 100,internal passage 82 down to a terminal end surface 96 and out throughthe open (unblocked) upper portion of slot 88, above surface 96, andinto the induction passage 12. Of course, such fuel flow will occur onlyas the throttle valve 20 is rotated so as to have edge 21 thereoftraverse the open portion of slot 88 and, in such case, only through somuch of that portion of the slot 88 as is exposed to the vacuum existingposterior to the throttle valve 20.

In view of the above, it should be apparent that the invention enablesthe construction and positioning of a transfer port or slot (defined bythe open portion of slot 88 above the level of surface 96 of plug 66 andrib 92) to exactly the desired position relative to the edge of therelated throttle valve regardless of the manufacturing tolerances.

FIGS. 6 and 7 illustrate what may be considered as second embodiments ofthe elements shown in FIG. 5. Elements of FIGS. 6 and 7 which are likeor similar to those of FIG. 5, or FIG. 3, or identified with likereference numbers with a suffix a.

In comparing insert body 64a to body 64 it can be seen that the onlyreal difference therebetween is the elimination of rib portion 84 inbody 64a and the enlargement of surfaces 86a which are totally exposedto the interior of the induction passage 18 as to form a wall portionthereof.

In comparing plug 66a to plug 66 it can be seen that plug 66a, inaddition to the rib 92a, has a further extension 102 with an abutmentsurface 104 formed thereon which, as indicated, may be generally steppedwith respect to top surface 96a.

The insert body 64a and plug 66a may be inserted within the receivingrecess 68a in the manner generally described with reference to body 64and plug 66 in FIG. 3. However, as will be noticed in FIG. 4, theabutment surface 104 enables the quick and accurate positioning of theplug 66a merely by abuttingly engaging the lower surface of edge 21a, ofthrottle valve 28, against abutment surface 104 and rotating thethrottle valve 28 to its idle position where, automatically, the properposition and relative location of upper surface 96a of plug 66a isachieved.

Although the insert body and cooperating plug of the invention may beformed from any suitable material, it is nevertheless contemplated thatacetal resin, a high melting, highly crystalline, thermoplastic polymerhaving a chemical structure represented by the formula (-OCH would behighly suited for their formation. In this connection, an acetal resinderived by polymerization of formaldehyde and sold commercially underthe trademark, Delrin, would be particularly suited. Delrin acetal resinhas been tested by the ASTM (American Society of Testing Materials) andthe results of such tests are available in ASTM report Nos. D-638,D-790, D-792 and D-696.

Further, if the components are to be cemented in place, variousadhesives could be employed among which could be a suitable epoxy.

Various modifications of the invention are, of course, possible. Forexample, the insert body, as 64, could be of a length equal to thelength of the cooperating receiving recess 68 so as to be axiallycontained between the gaskets 56 and 58.

Further, the insert body need not have a continuous slot, as at 88,formed therethrough. It is contemplated that in addition to possiblyproviding a contoured shape to the slot 88, the slot may be furthermodified by extending for only a portion of the length of body 64 withthe upper most portion of rib 84 being solid across the top resulting ina modified slot 88b as fragmentarily shown at FIG. 8. Such contouring ofthe slot may be desireable in certain instances in order to achieve atotally smooth transition from the idle system to the main fuel system.

Although only selected preferred embodiments and modifications of theinvention have been disclosed and described, it is apparent that otherembodiments and modifications of the invention are possible within thescope of the appended claims.

I claim:

1. Apparatus for defining a fuel discharge port in a fuel supply devicehaving a housing with an induction passage formed therethrough and avariably positionable throttle valve situated within said inductionpassage, comprising a body adapted to be inserted into a receivingopening formed in said housing, a first passage formed in said body forcommunication with a source of fuel, a slot-like opening formed in saidbody so as to complete communication between said first passage and saidinduction passage, and an end plugging member receivable within saidfirst passage, said plugging member being variably positionable in saidfirst passage and effective to define an end surface of said slot-likeopening, said plugging member being selectively positioned as to definesaid end surface at a selected position with respect to an edge of saidthrottle valve when said throttle valve is in a nominally closedposition.

2. Apparatus according to claim 1, wherein said plugging member includesa portion extending into said slot-like opening a distance sufficient tohave a terminal surface thereof substantially coextensive with thesurface of said induction passage.

3. Apparatus according to claim 1, wherein said plugging member includesa portion extending through said slot-like opening and projecting intosaid induction passage, said portion including a referenceabutmentsurface adapted to be operatively engaged by said edge of said throttlevalve whereby movement of said throttle valve to said nominally closedposition simultaneously causes corresponding movement of said pluggingmember to said selected position.

4. Apparatus according to claim 3, wherein said abutment surface isformed in a stepped relationship to said end surface in said slot-likeopening whereby said end surface may assume a justaposed position withrespect to said edge of said throttle valve when said throttle valveoperatively engages said abutment surface.

5. Apparatus according to claim 1, wherein said body is formed ofDelrin, and wherein said plugging member is formed of Delrin.

6. Apparatus according to claim 1, wherein said plugging member iscemented within said first passage so as to maintain its selectedposition within said body.

7. Apparatus according to claim; 1, wherein said slotlike openingextends for the entire length of said body.

8. Apparatus according to claim. 1, wherein said slotlike openingextends for the entire length of said first passage.

9. Apparatus according to claim 1, wherein said slotlike opening isclosed at one end, and wherein said one end is contoured as to present aprojected area of ever diminishing size as it more nearly approachessaid one

1. Apparatus for defining a fuel discharge port in a fuel supply devicehaving a housing with an induction passage formed therethrough and avariably positionable throttle valve situated within said inductionpassage, comprising a body adapted to be inserted into a receivingopening formed in said housing, a first passage formed in said body forcommunication with a source of fuel, a slot-like opening formed in saidbody so as to complete communication between said first passage and saidinduction passage, and an end plugging member receivable within saidfirst passage, said plugging member being variably positionable in saidfirst passage and effective to define an end surface of said slot-likeopening, said plugging member being selectively positioned as to definesaid end surface at a selected position with respect to an edge of saidthrottle valve when said throttle valve is in a nominally closedposition.
 2. Apparatus according to claim 1, wherein said pluggingmember includes a portion extending into said slot-like opening adistance sufficient to have a terminal surface thereof substantiallycoextensive with the surface of said induction passage.
 3. Apparatusaccording to claim 1, wherein said plugging member includes a portionextending through said slot-like opening and projecting into saidinduction passage, said portion including a reference abutment surfaceadapted to be operatively engaged by said edge of said throttle valvewhereby movement of said throttle valve to said nominally closedposition simultaneously causes corresponding movement of said pluggingmember to said selected position.
 4. Apparatus according to claim 3,wherein said abutment surface is formed in a stepped relationship tosaid end surface in said slot-like opening whereby said end surface mayassume a justaposed position with respect to said edge of said throttlevalve when said throttle valve operatively engages said abutmentsurface.
 5. Apparatus according to claim 1, wherein said body is formedof Delrin, and wherein said plugging member is formed of Delrin. 6.Apparatus according to claim 1, wherein said plugging member is cementedwithin said first passage so as to maintain its selected position withinsaid body.
 7. Apparatus according to claim 1, wherein said slot-likeopening extends for the entire length of said body.
 8. Apparatusaccording to claim 1, wherein said slot-like opening extends for theentire length of said first passage.
 9. Apparatus according to claim 1,wherein said slot-like opening is closed at one end, and wherein saidone end is contoured as to present a projected area of ever diminishingsize as it more nearly approaches said one end.